1. Field of the Invention
This invention relates to an improvement in a single beam type infrared gas analyzer which has a light source, a cell through which the light from the light source passes, and a detector receiving the light which has passed through the cell, positioned in series with each other, and a chopper for interrupting the light along the optical path thereof.
2. Description of the Prior Act
A single beam type non-dispersive infrared gas analyzer generally used as this kind of gas analyzer is shown in FIG. 1. This analyzer has a light source 21, a cell 22, a chopper 23 and a detector 24 in series in the recited order, and the cell is provided with a gas inlet 25 and a gas outlet 26 in portions of cell 22 which will not block the optical path of the light therethrough. This type of analyzer is defective in the following ways.
Specifically, dead spaces a, b and c are formed between the light source 21 and the cell 22, the cell 22 and the chopper 23, and the chopper 23 and the detector 24, respectively, so that gas existing in the spaces a, b and c creates a background effect and causes deterioration of measurement accuracy. Moreover, four windows 27 are provided along the optical path, each causing some loss of light energy.
Furthermore, gas containing the component to be measured will tend to flow in the shortest path from the gas inlet 25 to the gas outlet 26, and gas flow at the corners of cell 22 and at the cell windows 27 is slow, so that much time is required for displacement of all of the gas in the cell. Such a problem will also occur in a double beam type analyzer.